1. Field
The invention is in the field of methods and apparatus for conveying flowable materials, such as slurry explosives, into a mine.
2. State of the Art
In many mining applications it is necessary or desirable to employ explosives to loosen the material being mined. In the past, when used in underground mining, explosives have been packaged and lowered in a service cage to the appropriate level, and then trucked to the appropriate location for use.
Attention has lately been directed toward the feasbility of mining oil shale in order to extract the oil contained therein. However, this will require the use of vast quantitites of explosives. Inasmuch as service cage time for uses such as lowering explosives into a mine is very limited, it is necessary to devise a new method to convey large amounts of explosives down a mine shaft to the point of use within a mine.
In recent years, various formulations of slurry explosives have been developed so that now this type of explosive is preferred for most uses. However, explosives in general, including slurry explosives, cannot safely be dropped over long vertical distances because of the danger of explosion on impact or the danger of alternation of physical or chemical properties on impact. Further, for similar reasons, a high hydrostatic head on the material is undesirable. Thus, it would be both unsafe and impractical to merely drop the explosives down a mine shaft, or to have the explosives completely fill a conduit extending down a mine shaft.